1. Field of the Disclosure
This disclosure pertains in general to the field of membrane pumps or diaphragm pumps. More particularly the disclosure relates to membrane pumps used as sampling pumps in devices for patient monitoring, breath monitoring, anaesthesia monitoring, especially for medical ventilation monitoring and gas analyzers for monitoring gas composition in patient's breathing.
2. Description of Related Art
The membrane pumps have the advantages of simple, compact and good sealing. Membrane pumps have therefore been widely used in medical instrumentations and biochemical analysis as sampling pumps for fluid analysis. In the field of medical ventilation monitoring, the gas measurement module analyses gases extracted from patient breathing circuits by a membrane pump. This may be done for real time monitoring of gas composition in patient's breathing circuits and to get patient's status. Currently, the gas analysis module tends to be smaller with increased reliability and low power exhaust. Hence there are higher requirements for the design of membrane pumps concerning size, life and energy loss.
Gas monitoring instruments, such as sensors, used to detect gases are precision components sensitive to vibration interference which reduces the measurement accuracy. Under normal circumstances, the sampling pump is a main vibration source in a monitoring module. Thus may introduce noise which could affect the measurement accuracy. The sampling pump is therefore required to provide a more stable sample flow.
The normal design of a membrane pump has a flat membrane and a pump chamber which is either spherically concave or cylindrical with a flat bottom. Two examples of there types of pumps are Thomas membrane pump or Xavitech membrane pump. Also, membrane pumps have normally membranes that are fixed to outer edges of the membrane, thus defining a pump area. This design is limiting the elastic behaviours of the membrane, is limiting the stroke length and the pump area is limiting the maximum pump pressure (since the area together with the pump force is defining the maximum pump pressure) and the fatigue life. Other problems are when a flat membrane meets a concave or a flat surface of the pump chamber. This will generate noise and the pump stroke will stop instantly causing mechanical vibrations.
Hence, a new improved design of a membrane pump would be advantageous. Especially a smaller pump with a higher pressure having low vibrations and that runs quieter than known membrane pumps.